Embodiments of the invention are directed, in general, to communication systems and, more specifically, to de-rate matching in communication systems.
The following abbreviations may be utilized herein:                3GPP 3rd Generation Partnership Project        ACK acknowledgement        ARQ automatic repeat-request        BCH broadcast channel        BCCH broadcast control channel        BLER block error rate        CQI channel quality indicator        CRC cyclic redundancy check        D-BCH dynamic broadcast channel        DCCH dedicated control channel        DL downlink (Node B to UE)        DL-SCH downlink shared channel        DTCH dedicated traffic channel        E-UTRAN evolved universal terrestrial radio access network (LTE of UTRAN)        F filler bits        HARQ hybrid automatic repeat-request        L1 layer 1 (physical layer, PHY)        LTE long term evolution of UTRAN (E-UTRAN)        LLR Log-Likelihood Ratio        MAC medium access control (layer 2, L2)        MIB master information block        NACK negative acknowledgement        ND number of padding bits        Node B base station        PDCCH physical downlink control channel        RV redundancy version        rvidx redundancy version index        TTI Transmission Time Interval        UE user equipment, such as a mobile station or mobile terminal        UL uplink (UE to Node B)        
Consider the currently proposed channel coding of system information in E-UTRAN. One element comprises using the BCCH logical channel, as mapped to the BCH transport channel, to transmit at least a portion of system information. Currently, the transport format is of a fixed, though as yet unspecified (i.e., undetermined), size. The channel coding rate is assumed to be implicitly given by the combination of transport block size, modulation and resource assignment. Furthermore, no BCH HARQ is employed.
HARQ is a scheme for re-transmitting a packet to compensate for an erroneous packet. In particular, HARQ is useful for instances when an error occurs in the reception of an initially transmitted data packet. HARQ functionality helps ensure accurate delivery between peer entities at L1. HARQ uses multiple stop-and-wait processes operating in parallel. For example, for each transport block received in the UL, an acknowledgment is transmitted from the Node B to the UE after the receiver of the Node B performs a CRC to indicate a successful decoding (ACK) or to request a retransmission of the erroneously received transport block (NACK). UL signaling includes the one-bit HARQ positive/negative acknowledgement (HARQ-ACK/NACK), and five-bit measurement report (CQI), as non-limiting examples. At the Node B, the UL signaling information or status report is processed by a MAC sublayer. These ACK/NACK messages are generally transmitted with special physical layer signaling independent of data transmission.
HARQ may also be used in the DL in a similar manner. Currently, E-UTRAN utilizes HARQ in both the UL and DL. As such, for each transport block received in the DL by the UE, a HARQ message (i.e., ACK or NACK) is transmitted from the UE to the Node B. An ACK is signaled after the receiver of the UE performs a CRC that indicates a successful decoding while a NACK comprises a request for retransmission of an erroneously received (e.g., erroneously decoded) transport block.
Reference with regard to Universal Mobile Telecommunications System (UMTS) design document for channel coding to “3rd Generation Partnership Project 3GPP TS-36.212 v8.4.0 (Release 8) http://www.3gpp.org/ftp/specs/html-info/136212.htm; for Physical Layer Procedures to 3GPP TS-36.213 v8.4.0 (Release 8) hit http://www.3gpp.org/ftp/specs/html-info/36213.htm. Said documents incorporated by reference.